K-Polymer Composite Materials—A New Approach to Damage-Tolerant Aerospace Structures

The processing characteristics, mechanical properties and environmental resistance of fiber reinforced laminates based on a new family of amorphous thermoplastic polyimide matrix resins, designated K-polymers, are described,, Graphite fiber reinforced composites have been shown to possess excellent strength retention at temperatures as high as 232°C, excellent environmental resistance and unprecedented damage tolerance. Composites can be processed either by the vacuum bag/autoclave molding of tacky, drapable prepreg made using the polyimide precursor solutions or through automated tape laydown using a hot head acting on fully polymerized thermoplastic tape. These unique processing and product properties make K-polymers prime matrix resin candidates for use with high performance fibers such as graphite and “Kevlar” 49 for primary structures in aerospace applications.